moringa oleifera

What is Moringa oleifera

Moringa Oleifera also known as the moringa tree, the drumstick tree or the horseradish tree, is a small tree that is native to the foothills of the mighty Himalayan mountains in the northern part of India. For thousands of years, this small tree has been cultivated by different cultures throughout India and Africa because of its health benefits. However, it’s important to note that not all of the Moringa oleifera plant is safe, as toxic compounds have been found and that there are parts that can eventually harm people’s health 1). The most toxic part of Moringa oleifera is the bark and the root, and the safest part is the leaves; it is important to test their toxicity 2). Moringa oleifera leaf contains high amounts of crude protein, vitamin, mineral, and fatty acid. Moringa oleifera can provide 9 times more protein than yogurt, 17 times more calcium than milk, 7 times more vitamin C than oranges, 10 times more vitamin A than carrots, 25 times more iron than spinach, and 15 times more potassium than bananas 3). Given these excellent nutritional values, a daily intake of 10 g of Moringa oleifera leaf powder can help malnourished children to recover their body weights and enhance health indicators within a short time 4). Moreover, the consumption of Moringa oleifera leaf strengthens neural response, enhances immune functions, and improves health because of the large amounts of microelements and polyphenol antioxidants 5). Aside from promoting animal productivity and favorably influencing lipid composition, the potent antioxidant in Moringa oleifera leaf prevents meat products from deterioration 6). Studies have been carried out to evaluate the feeding effects of Moringa oleifera leaf meal on various animal species, including cattle 7), goats 8), chickens 9) and fish 10). All these studies concluded that Moringa oleifera leaf can be used as an alternative protein source for animal husbandry 11).

Beyond the uses of Moringa oleifera as a food and for human health, other possible uses exist. Moringa oleifera can be used as a natural plant growth enhancer; Moringa oleifera leaves are rich in zeatin (a plant hormone belong to the cytokinin group). Moringa oleifera leaf extracts can stimulate plant growth and increasing crop yield. Researches performed using a spray based on Moringa oleifera leaf extracts of wheat, maize and rice support the wide range of beneficial effect on crops 12). Moringa oleifera seed powder can be used for water purification, replacing dangerous and expensive chemicals such as aluminum sulfate 13). Interestingly, Moringa oleifera leaf extracts and also seed extracts show biopesticide activity, effective against larvae and adults of Trigoderma granarium and can reduce the incidence of fungi on groundnut seeds 14).

One of the interesting applications of Moringa oleifera seeds is their utilization as biomass for biodiesel production. Due to the increasing energy demand and environmental problems associated with fossil fuels, the improvement of alternative fuels and renewable sources of energy is required. Biodiesel can replace petroleum-derived oil (petrodiesel), without any sulphur or aromatic compound and with lower emission of monoxides, hydrocarbons and particulates. Furthermore, biodiesel can reduce dependence on imported fuels: a crucial problem in developing countries 15). Moringa oleifera seeds have an oil content of 30%–40%, with a high-quality fatty acid composition i.e., high oleic acid (>70%) 16). In addition they posses significant resistance to oxidative degradation. These proprieties make Moringa oil a good candidate to produce biodiesel after transesterificaton 17). Biswas and John 18), in a study conducted in Australia, report that approximately 3030 kg of oil are required to produce 1000 liters of biodiesel. Furthermore, an equivalent of 3.03 tonnes/hectare of oil seeds can be harvested from dry land, and 6.06 tonnes/hectare can be harvested from irrigated land. Since biodiesel production with Moringa oleifera seed oil is a second generation production (i.e., not in direct competition with existing farmland and with food crops) and as Moringa can grown on degraded land, studies suggest that Moringa biodiesel is an acceptable substitute to fossil fuels, even when compared against biodiesel derived from vegetable oil of other species 19).

Figure 1. Moringa oleifera tree

Moringa oleifera tree, flowers and leaves

Footnote: (a) A tree of Moringa oleifera; (b) Moringa flowers and leaves.

[Source 20) ]

Figure 2. Moringa oleifera bioactive compounds

Moringa oleifera bioactive compounds

Figure 3. Moringa oleifera leaves bioactive compounds chemical structures

Moringa oleifera leaves bioactive compounds chemical structures
[Source 21) ]

Moringa oleifera benefits

Moringa oleifera has several uses due to its composition. Moringa oleifera plants could be used for functional food and other industrial food applications 22). Moringa oleifera provides nutrients that benefit health, making it a key food for food security in areas with fewer economic resources 23). Moringa oleifera seed powder is used to purify water, eliminating a large amount of suspended material in rivers and turbid waters, making it a natural coagulant for water treatment. The oil from the Moringa oleifera seeds can be used as a fertiliser in plantations to encourage the growth of other species; it is also used for cosmetics such as soaps and perfumes 24) and even for the production of biodiesel 25). Moringa oleifera extracts can be used to produce zeatin effective for plant development, increasing crop yields 26). In addition to these applications, Moringa oleifera has been used in food, for example, in Mexico as an ingredient to partially replace fishmeal in tilapia feed, due to its protein and carbohydrate content 27).

Several bioactive compounds were recognized in the leaves of Moringa oleifera. They are grouped as vitamins, carotenoids, polyphenol, phenolic acids, flavonoids, alkaloids, glucosinolates, isothiocyanates, tannins, saponins and oxalates and phytates (see Figure 3 above). The amounts of different bioactive compounds found in Moringa oleifera leaves and reported in literature are summarized in Table 2, Table 3, Table 4, Table 5, Table 6, Table 7, Table 8, Table 9 and Table 10 below.

Moringa oleifera in food

The use of Moringa oleifera in food can be very beneficial; some researchers indicate that food products can be enriched with Moringa oleifera by providing vitamins, minerals, essential amino acids and oils in order to improve their nutritional value 28). Supplementation of Moringa oleifera powder in cereal porridge has been shown to improve the nutritional value by increasing the vitamin A content by up to 15 times. In the white maize variety, the protein content by fortification increased by 94% with 15% Moringa oleifera powder and for the yellow maize variety, the protein content increased by 44% 29). However, many studies have shown that products formulated with Moringa oleifera powder in high concentrations may be generally unacceptable to most consumers 30). Domenech et al. 31) reported that most Moringa oleifera is used almost exclusively in breads, biscuits and meat products, with its nutritional, technological and preservative purposes, respectively.

Moringa oleifera supplementation has a nutritional purpose, although it can provide other benefits to the product, such as improved digestibility 32), dough stability, antioxidant capacity, preservation, among other benefits associated with the plant. The use in bread and biscuits is a very useful strategy to make up for nutritional deficiencies, due to the high consumption of these foods. In addition, the food industry has tried to reduce the consumption of wheat flour in bakery products, in order to deliver foods that provide better nutritional characteristics, including reduced gluten, and for this, Moringa oleifera seems to be an option 33).

According to Ogunsina et al. 34), the incorporation of Moringa oleifera seed flour affects the organoleptic properties of different breads and biscuits; however, these differences are not significant when used in a ratio of 90% flour and 10% Moringa oleifera for bread and 80% flour and 20% Moringa oleifera for biscuits. Moreover, the taste was typical of Moringa oleifera seed, but acceptable in bread and the nutritional composition improved in both products, increasing the levels of protein, iron and calcium 35).

Chizoba et al. 36) also developed biscuits, substituting wheat flour with Moringa oleifera leaf flour; their results showed that the indicated proportion to maintain acceptable sensory characteristics and attributes is 90/10, that is to incorporate 10% of Moringa oleifera flour not exceeding 20% according to the authors 37).

The incorporation of Moringa oleifera seed meal in biscuits is reported to improve protein intake, increasing it by 45% to 90% if the addition of Moringa oleifera is 10% or 20% respectively. In the case of rice cakes, the addition of Moringa oleifera at 5% (freshly harvested) to 14% (dried) increases protein by approximately 26% 38).

Rabie et al. 39) also made biscuits fortified with Moringa oleifera leaf powder and seed powder in different concentrations, ranging from 2.5% to 7.5%. Their results found that supplementation with Moringa oleifera leaf powder has a higher amount of protein, ash, crude fiber, dietary fibre and minerals, while seed powder is characterised by a higher content of fat, protein, dietary fibre and minerals, and when mixed, a higher amount of essential amino acids was achieved, and when compared to the control, the biscuits with Moringa oleifera incorporation showed a lower carbohydrate content.

In relation to the physical characteristics, there is an increase in weight with a reduction in the volume and diameter of the biscuits, concluding that the best concentration to improve the nutritional characteristics without altering their organoleptic characteristics was 5% for the incorporation of leaf and seed powder and 2.5% + 5% in the case of mixing leaf and seed powder respectively 40).

Most of the evidence related to the incorporation of Moringa oleifera in cakes is associated with the consumption of biscuits, and in all reports, the results are similar. Supplementation increases nutritional value but affects physical characteristics, decreasing volume and colour in some instances; this was also demonstrated by a study by Nutan Narwal et al. 41).

The same would be true for the preparation of brownies and cakes with wheat flour, according to Santos et al. 42), who incorporated 5% and 10% Moringa oleifera leaf flour in chocolate brownies, indicating that the samples improved the nutritional value by increasing the ash content with a lower lipid contribution in relation to the control. A feature not mentioned in previous studies with biscuits is that the brownie showed the acidity of the product. The researchers concluded that there is no major difference between 5% and 10%, as similar results were obtained in both cases 43).

Whereas, in the wheat flour cake, the value of protein, moisture, crude fiber, total ash increased, with a reduction in lipids and carbohydrates, concluding that the cake sample with the addition of 4 g of Moringa oleifera was the most acceptable in terms of colour, flavour, aroma and overall acceptability 44).

In the case of bakery products, the use of Moringa oleifera powder in wheat flour bread dough as in other products increases the nutritional value, the protein and crude fiber content of wheat bread flour enriched with 5% Moringa oleifera powder has been found to increase from approximately 17% to 54% and 56% to 88% respectively. It should be noted that this improvement is accompanied by poor sensory properties, such as crust and crumb colour, as well as product weight and height 45).

Specifically for the case of whole wheat bread, El-Gammal et al. 46) added Moringa oleifera in different concentrations (5%, 10%, 15% and 20%); the results obtained indicated that Moringa oleifera leaf powder contained high amounts of protein and crude fibre, in addition to some essential minerals such as calcium, magnesium, phosphorus and iron. When Moringa oleifera was added to the preparation of wholemeal sliced bread, the protein content increased to 21.85%, the ash content (5.21%) and carbohydrate content decreased by 59.34%, and the intake of magnesium, calcium and iron increased compared to the control.

In relation to the undesirable effects of Moringa oleifera in bread incorporation, it negatively affects farinograph and extensometer values. Although there was an improvement in nutritional value, the acceptability of all loaf bread samples decreased with increasing levels of Moringa oleifera powder concentration, especially the loaf bread with 15 and 20%.

On the other hand, there are modifications in texture, taste, chewiness, elasticity of all samples compared to the control, however the researchers conclude that the best concentration to add to sliced bread is 5 or 10%, thus obtaining an increase in nutritional value with acceptable sensory characteristics 47).

Similar results were obtained by Bolarinwa et al. 48), who added Moringa oleifera seed powder to bakery products, increasing the protein value from 8.55 to 13.46%, ash from 0.63 to 1.76%, lipids from 7.31 to 15.75%, fibre from 0.08 to 0.62%, vitamin A from 50 to 74%, with a reduction in moisture from 22.9% to 20.01% and carbohydrates from 57.68% to 46.73%, also highlighting the increase in calcium, iron, phosphorus, and potassium in all its breads. Sensory evaluation results indicated that bread enriched with 5% Moringa oleifera seeds was not significantly different from the 100% wheat flour control 49).

Finally, while Devisetti et al. 50) evaluated the effect of Moringa oleifera leaf flour in sandwiches reaching similar conclusions, the protein content in puffed sandwiches increased, presenting 21.6 g in 100 g of product; while dietary fibre was presented at 14.8 g per 100 g of product, there was also a reduction in fat content of 3.7 g per 100 g of product with a high presence of phenolic compounds and flavonoids. In relation to the sensory characteristics of the sandwiches, an acceptable result was obtained in terms of texture 51).

Figure 4. Moringa oleifera use in bakery industry

Moringa oleifera use in bakery industry

Table 1. Moringa oleifera in bakery products and its effect on product quality

Bakery ProductsParts UsedMoringa oleifera Application/Concentration UsedMain Results/ConclusionsReference
CookiesMoringa oleifera leaves and seeds; and a combination of both.2.5%, 5%, 7.5%Moringa oleifera raised the nutritional value highlighting the amount of protein, ash, fibre and minerals. In addition, it showed an increase in weight without increasing the volume of the cookies compared to the control.52)
Bread and cookiesMoringa oleifera seed flour. 10%, 20%, 30%Bread with 10% and cookies with 20% of Moringa oleifera seed flour respectively had more protein, iron and calcium.53)
CookiesMoringa oleifera leaf flour10%, 20%, 30%, 50%Incorporation at 10% of Moringa oleifera leaf flour showed better sensory attributes; however, acceptability decreased as Moringa oleifera levels increased.54)
CookiesMoringa oleifera leaf flour5%Moringa oleifera supplementation at 5% of Moringa oleifera leaf flour raised the nutritional value of proteins and ash, showing a lower content of carbohydrates.55)
CookiesMoringa oleifera leaf flour0%, 10%, 20%, 30%, 50%The best acceptability in wheat flour biscuits supplemented with Moringa oleifera was shown by the concentration at 10% of Moringa oleifera leaf flour56)
Brownie (cake)Moringa oleifera leaf powder0%, 5%, 10%It improved the physicochemical characteristics; and a higher ash content and lower lipid content was found, compared to the control sample.57)
BreadMoringa oleifera leaf powder5%, 10%, 15%,20%Supplementation of Moringa oleifera leaf powder in bread raised the nutritional characteristics of proteins, ash and minerals; however, the carbohydrate content decreased. The acceptability decreases as the incorporation of Moringa oleifera increases, so the greater acceptability is at 5% and 10% of leaf powder.58)
BreadMoringa oleifera seed powder0–20%The results showed an increase in the value of proteins, minerals, ash, lipids, and fiber; however, there was a decrease in the value of carbohydrates. There were no sensory differences with the control when incorporating 5% of Moringa oleifera seed flour.59)
SnackMoringa oleifera leaf powder20%Snacks increased their nutritional value in protein and fiber, showing a low amount of fat. Furthermore, flavonoids were found in the final product.60)
Rice crackersMoringa oleifera leaves1%, 2%, 5%1% and 2% of Moringa oleifera leaves had higher levels of beta-carotene, vitamin C, and calcium than the control. Sensory scores were comparable to control even at the end of the storage test.61)
BreadMoringa oleifera leaf powder0%, 1%, 2%, 3%, 4%, 5%The nutritional composition of proteins, ash, fiber, minerals and β-carotene improved. Acceptability decreased when Moringa oleifera supplementation increased, affecting the bread physical and sensory attributes.62)

Alkaloids

Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This nitrogen may occur in the form of a primary amine (RNH2), a secondary amine (R2NH) or a tertiary amine (R3N). In addition to carbon, hydrogen and nitrogen, most alkaloids contain oxygen 63). Alkaloids are of particular interest thanks to their pharmacological properties. The presence of these compounds has been confirmed in Moringa oleifera leaves 64). Several of these compounds, such as N,α-l-rhamnopyranosyl vincosamide, 4-(α-l-rhamnopyranosyloxy) phenylacetonitrile (niazirin), pyrrolemarumine 4′′-O-α-l-rhamnopyranoside, 4′-hydroxy phenylethanamide-α-l-rhamnopyranoside (marumoside A) and its 3-O-β-d-glucopyranosyl-derivative (marumoside B) and methyl 4-(α-l-rhamnopyranosyloxy)-benzylcarbamate, have been isolated in Moringa oleifera leaves 65). However, their amounts in the Moringa oleifera leaves are still unknown.

Vitamins

Fresh leaves of Moringa oleifera are reported to contain 11,300–23,000 IU of vitamin A 66). Vitamin A plays key roles in many physiological processes such as vision, reproduction, embryonic growth and development, immune competence, cell differentiation, cell proliferation and apoptosis, maintenance of epithelial tissue, and brain function. Vitamin A deficiency is still prevalent in many developing countries, and considered responsible for child and maternal mortality 67).

Fresh Moringa oleifara leaves are also a good source of carotenoids with pro-vitamin A action. They contain 6.6–6.8 mg/100 g 68) of beta-carotene, greater that carrots, pumpkin and apricots (6.9, 3.6 and 2.2 mg/100 g, respectively).

Beta-carotene is more concentrated in the dried leaves, with amounts ranging from 17.6 to 39.6 mg/100 g of dry weight 69). This wide range may be explained by the different environmental conditions existing among different origin countries, genetic of the plant, drying method 70) and the different extraction and analysis methods employed as well. Freeze-drying seems to be the most conservative dehydration method. In freeze-drying leaves the β-carotene content is approximately 66 mg/100 g 71).

Moringa oleifera is an interesting source of vitamin C. Fresh leaves contain approximately 200 mg/100 g 72), greater than orange. These amounts are of particular interest, as the vitamin C intervenes in the synthesis and metabolism of many compounds, like tyrosine, folic acid and tryptophan, hydroxylation of glycine, proline, lysine carnitine and catecholamine. It facilitates the conversion of cholesterol into bile acids and hence lowers blood cholesterol levels and increases the absorption of iron in the gut by reducing ferric to ferrous state. Finally, it acts as antioxidant, protecting the body from various deleterious effects of free radicals, pollutants and toxins 73). However, being vitamin C sensitive to heat and oxygen, it is rapidly oxidized, so much so that its concentration in the Moringa oleifera dried leaves is lower than in the fresh leaves, dropping to 18.7 to 140 mg/100 g of dry weight 74).

Difference in (i) environmental conditions in the various origin countries; (ii) genetic of the plant; (iii) drying method 75) and (iv) different extraction and analysis methods, may explain the wide range of vitamin C content in Moringa leaves reported in literature. Freeze-drying seem to better preserve vitamin C from oxidation, so much so that greater amounts of this vitamin were found in leaves undergone to freeze-drying soon after the collection. In these latter, vitamin C concentration ranges between 271 and 920 mg/100 g of dry weight 76).

Moringa oleifera fresh leaves are a good source of vitamin E (in particular alpha-tocopherol) and contain approximately 9.0 mg/100 g 77) of this compound, similarly to nuts. Vitamin E acts mainly as liposoluble antioxidants, but it is also involved in the modulation of gene expression, inhibition of cell proliferation, platelet aggregation, monocyte adhesion and regulation of bone mass 78). Drying procedure determines a concentration of vitamin E up to values of 74.45–122.16 mg/100 g of dry weight 79).

Among vitamins of group B, only thiamine, riboflavin and niacin seem present in Moringa oleifera leaves. These vitamins mainly act as cofactors of many enzymes involved in the metabolism of nutrients and energy production, and their concentration in fresh leaves ranges between 0.06 and 0.6 mg/100 g, 0.05 and 0.17 mg/100 g and 0.8 and 0.82 mg/100 g for thiamine, riboflavin and niacin, respectively 80), similarly to fruits and vegetable. Only one study reported the contribution of vitamin B1, B2 and B3 of dried leaves of Moringa oleifera 81). Their concentrations were 2.85, 22.16 and 8.86 mg/100g of dry weight, respectively. However, the amount of riboflavin in dried leaves seems very high compared to that of fresh leaves. Further studies are needed to confirm these values. Finally, Girija et al. 82) showed an appreciable physiological availability of these three vitamins in leaves of Moringa oleifera (61.6%, 51.5% and 39.9%, respectively).

Scientists did not find studies about other vitamin of group B or vitamin D and K in Moringa oleifera leave; therefore further studies on this topic are needed.

Table 2. Vitamins content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Vitamins
Vitamin Afresh11,300 IU45,200 IUN/AN/AIndia83)
fresh23,000 IU92,000 IU aN/AN/ABrazil84)
Vitamin B1–Thiaminefresh0.06 mg/100 g0.24 mg/100 gN/AN/AIndia85)
fresh0.21 mg/100 g0.84 mg/100 gN/AN/AN/A86)
fresh0.6 mg/100 g2.58 mg/100 gN/AMicrobiological methodIndia87)
dried2.64 mg/100 g2.85 mg/100 gN/AN/AN/AN/A88)
Vitamin B2–Riboflavinfresh0.05 mg/100 g0.20 mg/100 gN/AN/AIndia89)
fresh0.05 mg/100 g0.20 mg/100 gN/AN/AN/A90)
fresh0.17 mg/100 g0.726 mg/100 gN/AMicrobiological methodIndia91)
dried20.5 mg/100 g22.16 mg/100 gN/AN/AN/AN/A92)
Vitamin B3–Niacinfresh0.8 mg/100 g3.20 mg/100 gN/AN/AIndia93)
fresh0.8 mg/100 g3.20 mg/100 gN/AN/AN/A94)
fresh0.82 mg/100 g3.5 mg/100 gN/AMicrobiological methodIndia95)
dried8.2 mg/100 g8.86 mg/100 gN/AN/AN/AN/A96)
Vitamin C–Ascorbic acidfresh220 mg/100 g880 mg/100 gN/AN/AIndia97)
dried17.3 mg/100 g18.7 mg/100 gN/AN/AN/AN/A98)
dried92 mg/100 g92 mg/100 gSun-drying for 4 daysN/AAOAC 2004India99)
140 mg/100 g140 mg/100 gShadow-drying for 6 days
56 mg/100 g56 mg/100 gOven-drying at 60 °C for 1 h
dried38.8 mg/100 g b38.8 mg/100 g bAir-dryingMetaphosphoric acidIndophenol titrationPakistan100)
freeze-dried271 mg/100 g271 mg/100 gFreeze-dryingDeionized waterColorimetric methodFlorida, USA101)
freeze-dried920 mg/100 g920 mg/100 gFreeze-drying6% metaphosphoric acidTitration against 2,6-dichlorophenolindophenolNicaragua102)
840 mg/100 g840 mg/100 gIndia
680 mg/100 g680 mg/100 gNiger
Vitamin E–Tocopherolfresh9.0 mg/100 g16.21 mg/100 gN-hexane + ethyl acetate + BHTReverse-phase HPLCMalaysia103)
dried113 mg/100 g122.16 mg/100 gN/AN/AN/AN/A104)
dried74.45 mg/100 g74.45 mg/100 gDrying at 60 °C for 8 hMicroscale saponification and extraction with n-hexaneHPLCMexico105)
dried77.0 mg/100 g85.08 mg/100 gAir-dried under shadeN/AHPLC FluorescenceSouth Africa106)

Abbreviations: a Obtained considering a moisture of 75%; b Mean value of samples collected in different seasons; N/A = Not available.

Table 3. Carotenoids content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Carotenoids
β-carotenefresh6.63 mg/100 g33.48 mg/100 gAcetone–n-hexaneHPLCTaiwan107)
fresh6.8 mg/100 g27.22 mg/100 gN/AN/AN/A108)
dried36 mg/100 g36 mg/100 gSun-drying for 4 daysN/AAOAC 2004India109)
39.6 mg/100 g39.6 mg/100 gShadow-drying for 6 days
37.8 mg/100 g37.8 mg/100 gOven-drying at 60 °C for 1 h
dried16.3 mg/100 g17.62 mg/100 gN/AN/AN/AN/A110)
dried18.5 mg/100 g20.44 mg/100 gAir-dried under shadeN/AHPLCSouth Africa111)
freeze-dried66 mg/100 g66 mg/100 gFreeze-dryingAcetoneHPLCFlorida, USA112)
Luteinfresh6.94 mg/100 g35.05 mg/100 gAcetone–n-hexaneHPLCTaiwan113)
freeze-dried102 mg/100 g102 mg/100 gFreeze-dryingAcetoneHPLCFlorida, USA114)

Abbreviations: N/A = Not available.

Polyphenols

Moringa oleifera dried leaves are a great source of polyphenols. Their concentrations range from 2090 to 12,200 mg gallic acid equivalent (GAE)/100 g of dry weight 115) (or 1600 to 3400 mg tannin acid equivalent (TAE)/100g of dry weight) 116). These amounts are greater than those found in fruits and vegetable 117). The different environmental conditions in the various origin countries, the harvesting season 118), the genetic of the plant, the drying method, the leaf maturity stage 119) and the extractive method used may explain such wide range of reported values. Principal polyphenol compounds in Moringa oleifera leaves are flavonoids and phenolic acids 120).

Table 4. Polyphenols content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Polyphenols
Total phenolsdried4581 mg GAE/100 g a4581 mg GAE/100 g aShade-dryingWater Soxhlet extraction for 18–20 hFolin-CiocalteauIndia121)
3602 mg GAE/100 g b3602 mg GAE/100 g b
dried3290 mg GAE/100 g3290 mg GAE/100 gN/A50% MeOHFolin-CiocalteauIndia122)
dried2090 mg GAE/100 g2090 mg GAE/100 gN/A50% MeOH, 100% MeOH and waterFolin-CiocalteauIndia123)
dried10,504 mg GAE/100 g10,504 mg GAE/100 gN/AWater at 80 °C for 2 hFolin-CiocalteauIndia124)
dried10,616 mg GAE/100 g c10,616 mg GAE/100 g cAir-drying80% MeOHFolin-CiocalteauPakistan125)
dried10,300 mg GAE/100 g10,300 mg GAE/100 gAir-drying100% MeOHExtraction by shakerFolin-CiocalteauPakistan126)
12,200 mg GAE/100 g12,200 mg GAE/100 g80% MeOH
9720 mg GAE/100 g9720 mg GAE/100 g100% EtOH
11,600 mg GAE/100 g11,600 mg GAE/100 g80% EtOH
dried9630 mg GAE/100 g9630 mg GAE/100 gAir-drying100% MeOHExtraction by refluxFolin-CiocalteauPakistan127)
10,700 mg GAE/100 g10,700 mg GAE/100 g80% MeOH
6160 mg GAE/100 g6160 mg GAE/100 g100% EtOH
8210 mg GAE/100 g8210 mg GAE/100 g80% EtOH
dried2070 mg TAE/100 g2070 mg TAE/100 gAir-dryingAcetone/Water (7:3)Folin-CiocalteauIndia128)
dried1600 mg TEA/100 g d1600 mg TEA/100 g dAir-drying80% EtOHFolin-CiocalteauNicaragua129)
3400 mg TEA/100 g e3400 mg TEA/100 g e
dried5350 mg CAE/100 g5350 mg CAE/100 gOven-drying at 60 °C for 24 hMaceration with 70% EtOHFolin-CiocalteauThailand130)
2930 mg CAE/100 g2930 mg CAE/100 gMaceration with 50% EtOH
3710 mg CAE/100 g3710 mg CAE/100 gPercolation with 70% EtOH
3280 mg CAE/100 g3280 mg CAE/100 gPercolation with 50% EtOH
4550 mg CAE/100 g4550 mg CAE/100 gSoxhlet extraction with 70% EtOH
4460 mg CAE/100 g4460 mg CAE/100 gSoxhlet extraction with 50% EtOH
freeze-dried1535.6 mg GAE/100 g1535.6 mg GAE/100 gFreeze-drying80% EtOHFolin-CiocalteauFlorida, USA131)

Abbreviations: a Mature/old leaves; b Tender/young leaves; c Mean value of samples collected in different seasons; d Extracted leaves; e Unextracted leaves; N/A = Not available; GAE = Gallic acid equivalent; TAE = Tannin acid equivalent; CAE = Chlorogenic acid equivalent.

Phenolic acids

Phenolic acids are a sub-group of phenolic compounds derived from hydroxybenzoic acid and hydroxycinnamic acid, naturally present in plants. Thanks to their documented effects on human health, the contribution of food-supplied phenolic acids is a subject of increasing interest. In particular, these compounds are mainly studied for their documented antioxidant, anti-inflammatory, antimutagenic and anticancer properties 132). Particularly abundant in fruit and vegetables, phenolic acids were found in great amounts in Moringa oleifera leaves too. In dried leaves, gallic acid seems to be the most abundant, with a concentration of approximately 1.034 mg/g of dry weight 133), although Bajpai et al. 134) only found poorly detectable amounts. The concentration of chlorogenic and caffeic acids ranges from 0.018 to 0.489 mg/g of dry weight and not detected to 0.409 mg/g of dry weight, respectively 135). Lower, but appreciable, concentrations were found for ellagic and ferulic acids. Their concentrations range from not detected to 0.189 mg/g and 0.078 to 0.128 mg/g of dry weight, respectively 136). Some of these compounds were found more concentrated in freeze-dried leaves. Specifically, Zhang et al. 137), in Moringa oleifera leaves harvested in Florida and subsequently freeze-dried, found approximately 6.457 mg/g of dry weight of o-coumaric acid and 0.536 mg/g of dry weight of caffeic acid, while p-coumaric, synaptic, gentistic and syringic acids were found in poorly detectable amounts. Like for the flavonoids, the different environmental conditions, harvesting season, genetic of the plant, drying method, leaf maturity stage, extraction method used and the different sensitivity of the analytical methods may have contributed to the high inter-study variation in the concentrations of phenolic acids in Moringa oleifera leaves.

Table 5. Phenolic acids content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Phenolic acids
Caffeic aciddriedNDNDN/A50% MeOHHPLC and MS/MSIndia138)
dried0.409 mg/g0.409 mg/gN/A50% MeOH, 100% MeOH and waterHPLCIndia139)
freeze-dried0.536 mg/g0.536 mg/gFreeze-drying80% EtOHHPLCFlorida, USA140)
Chlorogenic aciddried0.018 mg/g0.018 mg/gN/A50% MeOHHPLC and MS/MSIndia141)
dried0.489 mg/g0.489 mg/gN/AWater at 80 °C for 2 hHPLC and MS/MSIndia142)
o-Coumaric acidfreeze-dried6.457 mg/g6.457 mg/gFreeze-drying80% EtOHHPLCFlorida, USA143)
p-Coumaric acidfreeze-driedNDNDFreeze-drying80% EtOHHPLCFlorida, USA144)
Ellagic aciddriedNDNDN/A50% MeOH, 100% MeOH and waterHPLCIndia145)
dried0.009 mg/g0.018 mg/gN/A50% MeOHHPLC and MS/MSIndia146)
dried0.189 mg/g0.189 mg/gN/AWater at 80 °C for 2 hHPLC and MS/MSIndia147)
Ferulic aciddried0.078 mg/g0.078 mg/gN/A50% MeOHHPLC and MS/MSIndia148)
dried0.078 mg/g0.078 mg/gN/A50% MeOH, 100% MeOH and waterHPLCIndia149)
dried0.128 mg/g0.128 mg/gN/AWater at 80°C for 2 hHPLC and MS/MSIndia150)
Gallic aciddriedNDNDN/A50% MeOH, 100% MeOH and waterHPLCIndia151)
dried1.034 mg/g1.034 mg/gN/A50% MeOHHPLC and MS/MSIndia152)
dried1.034 mg/g1.034 mg/gN/AWater at 80 °C for 2 hHPLC and MS/MSIndia153)
Gentistic acidfreeze-driedNDNDFreeze-drying80% EtOHHPLCFlorida, USA154)
Sinapic acidfreeze-driedNDNDFreeze-drying80% EtOHHPLCFlorida, USA155)
Syringic acidfreeze-driedNDNDFreeze-drying80% EtOHHPLCFlorida, USA156)

Abbreviations: ND = Not detected; N/A = Not available.

Flavonoids

Flavonoids are a sub-group of polyphenolic compounds having a benzo-γ-pyrone structure and are ubiquitous in plants, as they are synthesized in response to microbial infections 157). Epidemiological studies have consistently shown that high intake of flavonoids has protective effects against many infectious (bacterial and viral diseases) and degenerative diseases such as cardiovascular diseases, cancers, and other age-related diseases 158). Moringa oleifera leaves are an interesting source of flavonoids compounds. Total flavonoids concentration in dried leaves ranges from 5.059 to 12.16 mg/g of dry weight 159), namely, close to or larger than that in many fruits and vegetable normally consumed 160). These values are the overall sum of the amounts of single flavonoids. However, some flavonoids were studied only by some authors and, therefore, these amounts may be inaccurate. The total concentration of flavonoids in freeze-dried leaves ranges from 21.0 to 61.62 mg rutein equivalent/g of dry weight 161). Myricetin, quercetin and kaempferol are the main flavonoids found in Moringa oleifera leaves. In dried leaves, myricetin concentration is approximately 5.804 mg/g of dry weight, while quercetin and kaempferol concentrations range from 0.207 to 7.57 mg/g of dry weight and not detectable amounts to 4.59 mg/g of dry weight, respectively 162). Higher amounts were found in freeze-dried leaves. In particular, quercitin and kaempferol concentrations range from 5.47 to 16.64 mg/g and 1.5 to 3.5 mg/g of dry weight, respectively 163). Isorhamnetin concentration in dried leaves is approximately 0.118 mg/g of dry weight 164), while, in freeze-dried leaves, its concentration is up to 7 times larger, ranging from 0.52 to 0.72 mg/g of dry weight 165). Other flavonoids, such as luteolin, apigenin, daidzein and genistein, were found in not detectable concentrations in Moringa oleifera leaves 166). However these compounds were investigated only in few studies and, therefore, further investigations are needed. In addition, in this case, the high inter-studies variations for these compounds may be explained taking into account different environmental conditions, harvesting season, genetic of the plant, drying method, leaf maturity stage, extraction method used and, finally, the different sensitivity of the analytical methods.

Table 6. Flavonoids content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Flavonoids
Total flavonoidsdried1.29 mg/g a5.059 mg/g aVacuum-dryingMeOH + HCl + ascorbic acidHPLC-DADTaiwan167)
dried6.0 mg/g a,b6.0 mg/g a,bAir-drying70% MeOH + 0.1% acetic acidLC/MSGhana168)
7.03 mg/g a,b7.03 mg/g a,bSenegal
12.16 mg/g a,b12.16 mg/g a,bZambia
dried31.28 mg QE/g31.28 mg QE/gN/AWater at 80 °C for 2 hHPLC and MS/MSIndia169)
dried27.0 mg QE/g c27.0 mg QE/g cShade-dryingWater Soxhlet extraction for 18–20 hColorimetric methodIndia170)
15.0 mg QE/g d15.0 mg QE/g d
dried96.12 mg ECE/100g e96.12 mg ECE/100 g eAir-drying80% MeOHColorimetric methodPakistan171)
dried60.6 mg CE/g60.6 mg CE/gAir-drying100% MeOHExtraction by shakerSpectrophotometric methodPakistan172)
86.6 mg CE/g86.6 mg CE/g80% MeOH
53.3 mg CE/g53.3 mg CE/g100% EtOH
62.1 mg CE/g62.1 mg CE/g80% EtOH
dried59.0 mg CE/g59.0 mg CE/gAir-drying100% MeOHExtraction by refluxSpectrophotometric methodPakistan173)
72.9 mg CE/g72.9 mg CE/g80% MeOH
41.9 mg CE/g41.9 mg CE/g100% MeOH
53.1 mg CE/g53.1 mg CE/g80% EtOH
dried25.1 mg IQE/g25.1 mg IQE/gOven-drying at 60° C for 24 hMaceration with 70% EtOHColorimetric methodThailand174)
12.3 mg IQE/g12.3 mg IQE/gMaceration with 50% EtOH
18.0 mg IQE/g18.0 mg IQE/gPercolation with 70% EtOH
14.6 mg IQE/g14.6 mg IQE/gPercolation with 50% EtOH
24.5 mg IQE/g24.5 mg IQE/gSoxhlet extraction with 70% EtOH
12.7 mg IQE/g12.7 mg IQE/gSoxhlet extraction with 50% EtOH
freeze-dried61.62 mg RE/g61.62 mg RE/gFreeze-drying80% EtOHSpectrophotometric methodFlorida, USA175)
freeze-dried44.3 mg RE/g44.3 mg RE/gFreeze-drying80% MeOHSpectrophotometric methodNicaragua India Niger176)
21.0 mg RE/g21.0 mg RE/gNicaragua India Niger
38.1 mg RE/g38.1 mg RE/gNicaragua India Niger
ApigenindriedNDNDN/AMeOH + HCl + ascorbic acidHPLCTaiwan177)
DaidzeindriedNDNDN/A50% MeOH, 100% MeOH and waterHPLCIndia178)
Epicatechinfreeze-dried5.68 mg/g5.68 mg/gFreeze-drying80% EtOHHPLCFlorida, USA179)
GenisteindriedNDNDN/A50% MeOH, 100% MeOH and waterHPLCIndia180)
Isorhamnetindried0.03 mg/g0.118 mg/gVacuum-dryingMeOH + HCl + ascorbic acidHPLCTaiwan181)
freeze-dried0.13 mg/g f0.52 mg/g f,gFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana182)
0.18 mg/g h0.72 mg/g g,h
Kaempferoldried0.04 mg/g0.04 mg/gAir-dryingMeOH + 1% v/v HCl + TBHQHPLCPakistan183)
driedNDNDN/A50% MeOHHPLC and MS/MSIndia184)
dried2.360 mg/g2.360 mg/gN/A50% MeOH, 100% MeOH and waterHPLCIndia185)
dried0.198 mg/g0.198 mg/gN/AWater at 80°C for 2 hHPLC and MS/MSIndia186)
dried0.36 mg/g1.412 mg/gVacuum-dryingMeOH + HCl + 10 mg ascorbic acidHPLCTaiwan187)
dried0.8 mg/g0.8 mg/gAir-drying70% MeOH + 0.1% acetic acidLC/MSGhana188)
1.23 mg/g1.23 mg/gSenegal
4.59 mg/g4.59 mg/gZambia
freeze-dried0.98 mg/g f3.92 mg/g f,gFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana189)
0.54 mg/g h2.16 mg/g g,h
freeze-dried2.25 mg/g2.25 mg/gFreeze-drying80% MeOHHPLC-DADNicaragua190)
1.75 mg/g1.75 mg/gIndia
1.05 mg/g1.05 mg/gNiger
freeze-dried2.9 mg/g d2.9 mg/g dFreeze-drying70% MeOHLC/MSMalawi191)
2.3 mg/g2.3 mg/gSenegal
3.5 mg/g3.5 mg/gNicaragua
0.3 mg/g c0.3 mg/g cECHO
0.16 mg/g d0.16 mg/g dECHO
LuteolindriedNDNDN/AMeOH + HCl + ascorbic acidHPLCTaiwan192)
Myricetindried5.804 mg/g5.804 mg/gAir-dryingMeOH + 1% v/v HCl + TBHQHPLCPakistan193)
Quercetindried0.281 mg/g0.281 mg/gAir-dryingMeOH + 1% v/v HCl + TBHQHPLCPakistan194)
dried0.207 mg/g0.207 mg/gN/A50% MeOHHPLC and MS/MSIndia195)
dried0.207 mg/g0.207 mg/gN/A50% MeOH, 100% MeOH and waterHPLCIndia196)
dried0.807 mg/g0.807 mg/gN/AWater at 80 °C for 2 hHPLC and MS/MSIndia197)
dried0.90 mg/g3.529 mg/gVacuum-dryingMeOH + HCl + 10 mg ascorbic acidHPLCTaiwan198)
dried5.2 mg/g5.2 mg/gAir-drying70% MeOH + 0.1% acetic acidLC/MSGhana199)
5.8 mg/g5.8 mg/gSenegal
7.57 mg/g7.57 mg/gZambia
freeze-dried3.21 mg/g f12.84 mg/g f,gFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana200)
4.16 mg/g h16.64 mg/g g,h
freeze-dried9.26 mg/g9.26 mg/gFreeze-drying80% MeOHHPLC-DADNicaragua201)
6.34 mg/g6.34 mg/gIndia
7.70 mg/g7.70 mg/gNiger
freeze-dried5.47 mg/g b5.47 mg/g bFreeze-drying70% MeOHLC/MSMalawi202)
9.1 mg/g9.1 mg/gSenegal
15.2 mg/g15.2 mg/gNicaragua
0.58 mg/g c0.58 mg/g cECHO
0.46 mg/g d0.46 mg/g dECHO
Rutindried0.390 mg/g0.390 mg/gN/A50% MeOH, 100% MeOH and waterHPLCIndia203)
driedNDNDN/A50% MeOHHPLC and MS/MSIndia204)
freeze-dried1.674 mg/g1.674 mg/gFreeze-drying80% EtOHHPLCFlorida, USA205)

Abbreviations: a Obtained from the sum of single flavonoids measured; b Mean value of different samples; c Mature/old leaves; d Tender/young leaves; e Mean value of samples collected in different seasons; f Vegetative plants; g Obtained considering a moisture of 75%; h Flowering plants; ND = Not detected; N/A = Not available; QE = Quercetin equivalent; ECE = Epicatechine equivalent; CE = Catechin equivalent; IQE = Isoquercetin equivalent; RE = Rutein equivalent.

Glucosinolates and isothiocyanates

Glucosinolates are a group of secondary metabolites in plants. Structurally they are beta-S-glucosides of thio-oxime-O-sulfates and synthesized from amino acids. Appreciable amounts of these compounds were found in Moringa oleifera leaves. In particular, around 116 and 63 mg/g of dry weight in young and older leaves, respectively, are reported 206) These amounts are close to, and in some case larger than, those found in many cruciferous vegetables (e.g., broccoli, cabbage, radish), mainly sources of these compounds 207). 4-O-(α-l-rhamnopyranosyloxy)-benzyl glucosinolate has been identified as the dominant leaf glucosinolate of Moringa oleifera and is accompanied by lower levels of three isomeric 4-O-(α-l-acetylrhamnopyranosyloxy)-benzyl glucosinolates, which reflect the three position of the acetyl group at the rhamnose moiety of the molecule 208). The concentrations of these compounds seem affected by the physiological stage of the plant and by the maturity stage of the leaves. The concentration of 4-O-(α-l-rhamnopyranosyloxy)-benzyl glucosinolate ranges from 21.84 to 59.4 mg/g of dry weight, while the concentrations of the three isomer of 4-O-(α-l-acetylrhamnopyranosyloxy)-benzyl glucosinolates range from 2.16 to 5.0 mg/g of dry weight, 1.2 to 1.8 mg/g of dry weight and 12.76 to 50.2 mg/g of dry weight for isomer 1, 2 and 3, respectively 209). Amaglo et al. 210) report the presence of 4-hydroxybenzyl (sinalbin), with a concentration ranging between not detected and 2.36 mg/g of dry weight. Glucosinolates can be hydrolyzed by myrosinase to produce d-glucose and various other degradation products like isothiocyanates 211), which are also present in Moringa oleifera leaves 212). Both glucosinolates and isothiocyanates play an important role in health promoting and prevention of disease 213).

Table 7. Glucosinolates content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Glucosinolates
Benzylfreeze-driedND a ND bND a ND bFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana214)
freeze-driedND c ND dND c ND dFreeze-drying70% MeOHLC/MSMany countries215)
4-hydroxybenzyl (sinalbin)freeze-dried0.59 mg/g a ND b2.36 mg/g a,e ND b,eFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana216)
4-(α-L-rhamnopyranosyloxy)-benzylfreeze-dried5.64 mg/g a22.56 mg/g a,eFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana217)
5.46 mg/g b21.84 mg/g b,e
freeze-dried33.9 mg/g c33.9 mg/g cFreeze-drying70% MeOHLC/MSMany countries218)
59.4 mg/g d59.4 mg/g d
4-O-(α-L-acetylrhamnopyranosyloxy)-benzyl isomer 1freeze-dried0.69 mg/g a2.76 mg/g a,eFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana219)
0.54 mg/g b2.16 mg/g b,e
freeze-dried2.9 mg/g c2.9 mg/g cFreeze-drying70% MeOHLC/MSMany countries220)
5.0 mg/g d5.0 mg/g d
4-O-(α-L-acetylrhamnopyranosyloxy)-benzyl isomer 2freeze-dried0.45 mg/g a1.80 mg/g a,eFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana221)
0.38 mg/g b1.52 mg/g b,e
freeze-dried1.2 mg/g c1.2 mg/g cFreeze-drying70% MeOHLC/MSMany countries222)
1.5 mg/g d1.5 mg/g d
4-O-(α-L-acetylrhamnopyranosyloxy)-benzyl isomer 3freeze-dried5.04 mg/g a20.16 mg/g a,eFreeze-drying70% MeOHHPLC-DAD-electrospray mass spectrometryGhana223)
3.19 mg/g b12.76 mg/g b,e
freeze-dried17.4 mg/g c17.4 mg/g cFreeze-drying70% MeOHLC/MSMany countries224)
50.2 mg/g d50.2 mg/g d

Abbreviations: a Vegetative plants; b Flowering plants; c Mature/old leaves; d Tender/young leaves; e Obtained considering a moisture of 75%; ND = Not detected.

Tannins

Tannins are water-soluble phenolic compounds that bind to and precipitate alkaloids, gelatin and other proteins. They exhibit various biological properties: anti-cancer, antiatherosclerotic, anti-inflammatory, anti-hepatoxic, antibacterial and anti-HIV replication activity 225). Moringa oleifera leaves are an appreciable source of tannins. Their concentrations range between 13.2 and 20.6 gTAE/kg [68,69,76] in dried leaves and between 5.0 and 12.0 g tannin acid equivalent (TAE)/kg in freeze-dried leaves 226). These amounts are greater than concentrations found in nuts 227), similar to those found in some plants 228) and berries 229), but much lower compared to the concenctrations found in other medicinal plants 230).

Table 8. Tannins content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Tannins
Total tanninsdried13.2 gTAE/kg13.2 gTAE/kgAir-dryingAcetone/Water (7:3)Folin-Ciocalteau modifiedIndia231)
driedND a 14.0 gTAE/kg bND a 14.0 gTAE/kg bAir-drying80% EtOHFolin-Ciocalteau modifiedNicaragua232)
dried20.6 g/kg20.6 g/kgAir-drying at 35 °C for 24 hDouble lipid extraction with n-hexane (1:5)N/ABrazil233)
freeze-dried12 g/kg12 g/kgFreeze-drying80% MeOHFolin-Ciocalteau modifiedNicaragua234)
freeze-dried5 g/kg5 g/kgFreeze-drying80% EtOHFolin-Ciocalteau modifiedNiger235)
Condensed tanninsdried1.05 gLE/kg1.05 gLE/kgAir-dryingAcetone/Water (7:3)Butanol–HCl–iron methodIndia236)
dried3.12 g/kg3.12 g/kgAir-dried under shadeN/AButanol–HCl–iron methodSouth Africa237)

Abbreviations: a Extracted leaves; b Unextracted leaves; TAE = Tannin acid equivalent; LE = Leucocyanidin equivalent; ND = Not detected; N/A = Not available.

Saponins

Saponins are a group of natural compounds that consist of an isoprenoidal-derived aglycone, designated genin or sapogenin, covalently linked to one or more sugar moieties 238). Even though some saponins have hemolytic side effects, they are studied for their anti-cancer properties 239). Moringa oleifera leaves are a good source of saponins. Their concentration in dried leaves is approximately 50 g diosgenin equivalent (DE)/kg of dry weight 240), while in freeze-dried leaves it ranges between 64 and 81 g diosgenin equivalent (DE)/kg of dry weight 241). These amounts are greater than the concentrations found in other plants 242), but slighty lower than ginseng root 243), one of the mainly source of these compounds.

Table 9. Saponins content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Saponins
Total saponinsdried2.0 g DE/kg a2.0 g DE/kg aAir-drying80% EtOHSpectrophotometric methodNicaragua244)
50.0 g DE/kg b50.0 g DE/kg b
freeze-dried81 g DE/kg81 g DE/kgFreeze-drying80% MeOHSpectrophotometric methodNicaragua245)
freeze-dried64 g DE/kg64 g DE/kgFreeze-drying80% EtOHSpectrophotometric methodNiger246)

Abbreviations: a Extracted leaves; b Unextracted leaves; DE = Diosgenin equivalent.

Oxalates and phytates

Oxalates and phytates are anti-nutritional compounds as they bind minerals inhibiting the intestinal absorption. Moringa oleifera leaves present high contents of these compunds. Oxalates content of dried leaves range from 430 to 1050 mg/100 g of dry weight 247), similar to other plants rich in these compounds 248), while phytates concentration range from 25 to 31 g/kg of dry weight [69] in dried leaves and from 21 and 23 g/kg of dry weight in freeze-dried leaves 249). These amounts are greater than those found in legumes and cereals 250), but lower than brans 251).

Table 10. Oxalates and phytates content in Moringa oleifera leaves

Bioactive CompoundLeavesValue Found in LiteratureValue Express as Dry WeightDrying MethodExtractive MethodAnalytical MethodCountryReference
Oxalates and phytates
Oxalatesdried430 mg/100 g430 mg/100 gSun-drying for 4 daysN/AAOAC 2004India252)
500 mg/100 g500 mg/100 gShadow-drying for 6 days
450 mg/100 g450 mg/100 gOven-drying at 60 °C for 1 h
dried1050 mg/100 g1050 mg/100 gAir-drying at 35 °C for 24 hDouble lipid extraction with n-hexane (1:5)N/ABrazil253)
Phytatesdried25.0 g/kg a25.0 g/kg aAir-drying3.5% HCl for 1 hColorimetric methodNicaragua254)
31.0 g/kg b31.0 g/kg b
freeze-dried21.0 g/kg21.0 g/kgFreeze-drying3.5% HCl for 1 hColorimetric methodNicaragua255)
freeze-dried23.0 g/kg23.0 g/kgFreeze-drying3.5% HCl for 1 hColorimetric methodNiger256)

Abbreviations: a Extracted leaves; b Unextracted leaves; N/A = Not available.

Moringa oleifera traditional uses

All plant parts of Moringa oleifera are traditionally used for different purposes, but leaves are generally the most used 257). In particular, Moringa oleifera leaves are used in human and animal nutrition and in the traditional medicine. Moringa oleifera leaves are rich in protein, mineral, beta-carotene and antioxidant compounds, which are often lacking among the populations of underdeveloped or developing countries. Moringa oleifera leaves are added to food preparations as integrators of the diet. In traditional medicine, Moringa oleifera leaves are used to treat several ailments including malaria, typhoid fever, parasitic diseases, arthritis, swellings, cuts, diseases of the skin, genito-urinary ailments, hypertension and diabetes 258). Moringa oleifera leaves are also used to elicit lactation and boost the immune system (to treat HIV/AIDS related symptoms) 259), as well as cardiac stimulants and contraceptive remedy. One can directly consume either raw and dried leaves or the extract of an aqueous infusion.

Similarly, the use of Moringa oleifera seeds concerns both human nutrition and traditional medicine. Moringa oleifera tree barks are boiled in water and soaked in alcohol to obtained drinks and infusions that can be used to treat stomach ailments (ease stomach pain, ulcer and aiding digestion), poor vision, joint pain, diabetes, anemia and hypertension 260), toothache, hemorrhoids, uterine disorder 261). Moringa oleifera seeds are used to sediment impurities of water 262).

Moringa oleifera roots are soaked in water or alcohol and boiled with other herbs to obtained drinks and infusions as remedies for toothache, as anthelmintic and antiparalytic drugs and as sex enhancers 263).

Moringa oleifera flowers are used to produce aphrodisiac substances and to treat inflammations, muscle diseases, hysteria, tumors and enlargement of the spleen 264).

Moringa oleifera health benefits

Moringa oleifera has been used as a medicine in India since the 18th century BC 265). Traditional healers used different parts of the Moringa oleifera plant as traditional medicines. The medicinal uses are numerous and have long been recognised as an Ayurvedic and Unani system of medicine. Almost all parts of the Moringa oleifera plant: root, bark, gum, leaf, fruit (pods), flowers, seeds and seed oil, have been used to treat various diseases, like skin infections, swelling, anemia, asthma, bronchitis, diarrhea, headache, joint pain, rheumatism, gout, heart problems, fevers, digestive disorders, wounds, diabetes, conjunctivitis, hemorrhoids, goitre, earache, measles and smallpox in the indigenous system of medicine 266). Moringa oleifera leaf extract has been observed to decrease the conversion of T4 to T3 in female but not in male adult Swiss rats, therefore increasing the T4/T3 ratio, indicating a potential use for therapy of hyperthyroidism 267). Moringa oleifera is used as a galactogogue (help a breastfeeding mother to increase her breast milk supply) in Asia, particularly in the Philippines where it is called malunggay 268). Two small studies from the Philippines indicate that it might have some activity as a galactogogue in mothers of preterm infants 269), 270). Galactogogues should never replace evaluation and counseling on modifiable factors that affect milk production 271). Moringa oleifera leaves are widely used as a food and medicine in Asia and Africa and one small study found no adverse effects in nursing mothers who ingested Moringa leaves 272). No data exist on the safety of Moringa oleifera in nursing infants 273).

The bioactive compounds (Figure 3) present in Moringa oleifera confer properties associated with disease prevention and treatment, such as antimicrobial 274), anti-inflammatory 275), anticancer, antidiabetic, antioxidant, hepatoprotective and cardioprotective 276). Primary and secondary metabolites may also be involved in these applications. Primary metabolites are proteins, polysaccharides and lipids involved in physiological functions. Among them, polysaccharides and fibers are the main compounds showing positive effects on chronic diseases such as cancer, cardiovascular diseases, diabetes and obesity. On the other hand, secondary metabolites are minor molecules, such as phenolic compounds, halogenated compounds, sterols, terpenes and small peptides. Most of the phytochemicals reported in Moringa oleifera offer potential in the prevention and treatment of diseases.

The anti-inflammatory effect is due to the content of flavonoids, alkaloids, tannins and glycosides, among which quercetin appears to inhibit NF-KB activation, producing an anti-inflammatory effect 277). Other compounds with an anti-inflammatory effect include kaempferol derivatives, flavonol glycosides 278), aurantiamide acetate, 1,3-dibenzylurea 279), diterpenes, α- and β-amyrin 280), benzaldehyde 4-0-β-glucoside 281), β-sitosterol 282), rutin 283) and glucosinolate, mainly attributed to the glycosylate isothiocyanate, 4-(α-L-rhamnosyloxy) benzyl ITC, resulting from myrosinase 284). Moringa oleifera reduces inflammation by suppressing inflammatory enzymes and proteins in the body, and leaf concentrate can significantly reduce inflammation in cells 285).

The antimicrobial effect provided essential oils from the leaves and alcoholic extracts of the Moringa oleifera seeds. Martín et al. 286) demonstrated this activity of the leaf and leaves against dermatophytes such as Trichophyton rubrum and Trichophyton mentagrophytes. In addition to these compounds, other compounds have been found that also produce this effect, 4(βL-rhamnosyloxy) benzyl isocyanate or pterigospermine,4-(β-D-glucopyranosyl-1→4-β-l-ramnopyranosyloxy),benzyl thiocarboxamide,(-)-Catechin, phenylmethanamine, 4β-D-glucopyranosyl-1–>4 β-L-rhamnopyranosyloxy)-benzyl isocyanate, niazirine 287) and glucosinolate mainly attributed to the glycosylate isothiocyanate, 4-(α-L-rhamnosyloxy) benzyl ITC, resulting from myrosinase 288).

Phenolic compounds have been associated with the antimicrobial and antifungal activities of Moringa oleifera extracts 289), the Moringa oleifera leaves being the organs with the highest amount of these compounds. Regarding the antimicrobial effect of Moringa oleifera plants when included in food, Moringa Oleifera contributes to control the growth of undesirable microorganisms, due to low pH values and the presence of pterigospermin 290). The roots of Moringa oleifera have antibacterial properties and are described to be rich in antimicrobial agents. The bark extract has been found to have antifungal activities, while the juice of the bark and stem show an antibacterial effect against Staphylococcus aureus 291).

Studies have shown the anticarcinogenic effect of several compounds, namely glycosylated isothiocyanate, benzyl carbamate niazimycin and β-sitosterol, which have antitumour properties against lung, breast, skin, oesophageal and pancreatic cancer. These compounds are found in high concentrations in Moringa oleifera leaves and seeds 292). Moringa oleifera is rich in ascorbic acid, which provides an anti-diabetic effect by aiding insulin secretion, and another compound found in Moringa Oleifera that produces this effect is myricetin 293).

Antioxidants are popular because they scavenge free radicals that cause oxidative stress, cell damage and inflammation. Moringa oleifera contains antioxidants called flavonoids, polyphenols and ascorbic acid in the leaves, flowers and seeds 294). Studies have shown that the Moringa oleifera plant is rich in polyphenols, which gives it a high antioxidant capacity. The compounds in Moringa oleifera that provide this activity are feluric, gallic and ellagic acids, β-sitosterol, myricetin, niazimycin, niacimicin A and B, tocopherols: α-tocopherol, δ-tocopherol, γ-tocopherol, vanillin, kaempferol, quercetin, β-carotene (-)-catechin, astragalin and isoquercetin 295).

Moringa oleifera plays an important role in protecting the liver from damage, oxidation and toxicity due to the high concentrations of polyphenols in its leaves and flowers 296). Moringa oleifera oil can also restore liver enzymes to normal levels, reducing oxidative stress and increasing protein content in the liver. The flowers and roots of the Moringa oleifera plant contain a compound called quercetin, which is known to protect the liver 297). Other compounds contained in the plant with this activity are β-sitosterol, quercetin and some of its glycosides, rutin 298) and flavonoids, which also prevent lipid oxidation 299).

Moringa oleifera leaves and seeds have been found to help lower blood pressure; this is due to compounds called glycosides 300) and in the leaves it is also due to N-α-L-rhamnophyranosyl vincosamide 301). Moringa oleifera leaf extract has also been found to significantly reduce cholesterol levels due to the action of beta-sitosterol 302).

Analgesic, anti-inflammatory and antipyretic activities

Almost every part of Moringa oleifera has been found to exhibit analgesic activity in different animal models. Extract of Moringa oleifera leaves, seeds, and bark showed significant analgesic activity in both central (hot plate method) and peripheral models (acetic acid–induced writhing method) in a dose-dependent manner 303) and extracts of leaves exhibited analgesic potency similar to that of indomethacin 304) and antimigraine properties in a dose-dependent manner 305). Topical application showed efficacy against multiple sclerosis–induced neuropathic pain 306).

Anti-inflammatory activity of Moringa oleifera leaf extract has been observed in a carrageenan-induced paw edema model 307). Extracts of Moringa oleifera bark showed anti-inflammatory activity comparable to diclofenac in the same model. Anti-inflammatory properties of Moringa oleifera root have also been reported 308). Mechanism underlying the anti-inflammatory activity may be attributed to the regulation of neutrophils and c-Jun N-terminal kinase pathway 309) Active ingredients contributing to anti-inflammatory property are tannins, phenols, alkaloids, flavonoids, carotenoids, β-sitosterol, vanillin, hydroxymellein, moringine, moringinine, β-sitostenone, and 9-octadecenoic acid 310).

Moringa oleifera leaf extract showed significant antipyretic activity in a Brewer’s yeast–induced pyrexia model 311). Ethanol and ethyl acetate extracts of Moringa oleifera seeds also showed significant antipyretic activity 312).

Anticancer activity

Alcoholic and hydromethanolic extracts of Moringa oleifera leaves and fruits showed a significant growth delay in tumor kinetics in mouse melanoma tumor model studies 313). Extract of Moringa oleifera leaf also exhibited antiproliferative activity on A549 lung cells 314). Exploration of effects on prerequisites for cancer metastasis showed that the administration of Moringa oleifera leaf extract into chick chorioallantoic membrane led to an antiangiogenic effect, which was dose dependent, thereby showing their remarkable anticancer potential 315). Another study reported that Moringa oleifera pod extract suppressed azoxymethane and dextran sodium sulfate–induced colon destruction in male, Institute of Cancer Research mice 316). An extract of Moringa oleifera root and leaf showed a cytotoxic effect against breast cancer, hepatocarcinoma, and colorectal cancer cells in vitro and cisplatin-resistant ovarian cancer cells 317). Flower extract stimulated cell proliferation in normal cells but not in cancer cells, whereas leaf extract showed marked antitumor and hepatoprotective effects, these findings suggest the regenerative potential of Moringa oleifera besides its anticancer effects 318).

Phytoconstituents such as niazimicin, carbamates, thiocarbamate, nitrile glycosides and others such as quercetin and kaempferol are responsible for the anticancer activity of Moringa oleifera plant 319).

Antioxidant activity

Moringa oleifera fruits and leaves have antioxidant properties 320). Extract of Moringa oleifera leaf showed a concentration-dependent increase in glutathione level and a decrease in malondialdehyde level, fruit extract showed beneficial results in eliminating free radicals, extract of roots significantly reduced iron and FeSO4-induced microsomal lipid peroxidation in a dose-dependent manner 321). Pods were capable of scavenging peroxyl, superoxyl, and 2, 2-diphenyl-2-picryl hydrazyl (DPPH) radicals 322).

Besides displaying antioxidant activity, Moringa oleifera leaf extract also showed a dose-dependent nephroprotective action in an acetaminophen-induced nephrotoxicity model in male BALB/c rats 323). Triterpenoids, moringyne, monopalmitic and di-oleic triglyceride, campesterol, stigmasterol, β-sitosterol, avenasterol, vitamin A, and its precursor beta-carotene have been shown to contribute for antioxidant properties 324).

Neuropharmacological activity

Aqueous extract of leaves has shown protection against Alzheimer’s disease in a colchicine-induced Alzheimer’s model using behavioral testing (radial Y arm maze task) 325). It protected against Alzheimer’s disease by altering brain monoamine levels and electrical activity 326). Another study using toluene-ethyl acetate fraction of methanolic extract of Moringa oleifera leaf showed potent nootropic activity 327). Leaf extract contains vitamins C and E, which play a significant role in improving memory in patients with Alzheimer’s disease 328).

Anticonvulsant activity of Moringa oleifera leaves was shown in both pentylenetetrazole and maximum electric shock models using male albino mice 329). Aqueous extract of Moringa oleifera root suppressed penicillin-induced epileptic seizures in adult albino rats 330).

Ethanolic extract of Moringa oleifera leaves exhibited both central nervous system depressant and muscle relaxant activities in actophotometer and rotarod apparatuses, respectively 331) and also exhibited significant anxiolytic activity in staircase test and elevated plus maze test in a dose-dependent manner 332).

Effects on the reproductive system

Moringa oleifera leaf extract showed a significant increase in the weight of testis, seminal vesicle, epididymis, and a higher score for epididymal maturity and lumen formation along with an increase in seminiferous tubule diameter (all doses) 333).

Ethanolic extract of Moringa oleifera leaf protected prepubertal spermatogonial cells in Swiss male albino mice in cyclophosphamide-induced damage model; the possible underlying mechanism may be upregulation of expression of c-Kit and Oct4 transcripts independent of p53-mediated pathway 334).

The abortive effect of Moringa oleifera leaf extract on rats after treatment for 10 days after insemination has been reported 335). Moringa oleifera leaf extract showed a synergistic effect with estradiol and an inhibitory effect with progesterone 336). Fresh leaves of Moringa oleifera contain approximately 11,300–23,000 IU of vitamin A, which has a major role in various anatomical processes, such as reproduction, embryonic growth and development, immunity development, and cell differentiation 337).

Hepatoprotective activity

Extract of Moringa oleifera leaves has shown hepatoprotective effects against carbon tetrachloride and acetaminophen-induced liver toxicity in Sprague Dawley rats 338) and also hepatoprotective effect against antitubercular drugs and alloxan-induced liver damage in diabetic rats 339). Moringa oleifera plant-based diet for 21 days showed significant potential in attenuating hepatic injury 340). Alkaloids, quercetin, kaempferol, flavonoids, ascorbic acid, and benzylglucosinolate were found to be responsible for hepatoprotective activity 341).

Gastroprotective and anti-ulcer activities

Extract of Moringa oleifera leaves remarkably reduced ulcer index in ibuprofen-induced gastric ulcer model and in pyloric ligation test 342) and a significant reduction in cysteamine-induced duodenal ulcers and stress ulcers was also observed 343). Bisphenols and flavonoids could be contributing to this property 344).

Cardiovascular activity

Extract of Moringa oleifera leaf significantly reduced cholesterol levels and displayed a protective role on hyperlipidemia induced by iron deficiency in male Wistar rats 345). Antihypertensive effect of Moringa oleifera leaf extract on spontaneous hypertensive rats was shown, in addition to reduced chronotropic and inotropic effects in isolated frog hearts 346). Active constituents for hypotensive action are niazinin A, niazinin B, and niazimicin 347). Extract of Moringa oleifera leaves also showed cardioprotective effects against isoproterenol-induced myocardial infarction in male Wistar albino rats; the mechanism underlying this cardioprotective activity was found to be antioxidant effect, prevention of lipid peroxidation, and protection of histopathological and ultrastructural disturbances caused by isoproterenol 348).

A study was done of Moringa oleifera Lam. on various tissue systems and it showed reduction in inflammation and lipid accumulation 349).

Weight loss activity

Significant reduction in body mass index (BMI) was observed after oral treatment with Moringa oleifera leaf powder compared with that in obese control 350). Treatment of hypercholesterolemia rats with methanolic extract of Moringa oleifera leaf for 49 days showed a remarkable reduction in total cholesterol, triglycerides, and body weight, moreover, liver biomarkers, organ weight, and blood glucose levels were also decreased 351). Mechanisms include downregulation of mRNA expression of leptin and resistin and upregulation of adiponectin gene expression in obese rats 352).

Antiasthmatic activity

Extract of Moringa oleifera seeds showed protection against asthma as investigated in various models; the proposed mechanism for this effect was a direct bronchodilator effect combined with anti-inflammatory and antimicrobial actions 353) and inhibition of immediate hypersensitive reaction 354). Ethanol extract of Moringa oleifera seeds tested against ovalbumin-induced airway inflammation in guinea pigs showed a significant increase in respiratory parameters and reduction in interleukins in bronchoalveolar lavage 355).

Hematological activity

A randomized, double-blind, placebo-controlled study was carried out on women who were anemic with hemoglobin levels between 8 and 12g/dL and were treated with aqueous extract of Moringa oleifera leaf, the results showed an increase in mean hemoglobin and mean corpuscular hemoglobin concentration 356). Another study revealed that when Moringa oleifera was given to healthy human volunteers for 14 days, a significant improvement in platelet count was observed 357).

Anti-diabetic activity

Extract of Moringa oleifera leaf showed significant antihyperglycemic and hypoglycemic activity in normal and alloxan-induced diabetic rats 358). An elaborate study was performed to determine the effect of aqueous Moringa oleifera leaf extract on lipid profile, body weight, glucose, plasma insulin, homeostatic model assessment, and oral glucose tolerance test in insulin-resistant and type 1 diabetic rat models. Insulin resistant rats were fed a high-fructose diet, and type 1 diabetic rats were treated with Streptozotocin (55 mg/kg). Insulin-resistant rats showed an increase in hyperinsulinemia, hyperglycemia, and body weight, whereas Streptozotocin-induced diabetic rats showed hyperinsulinemia and hyperglycemia. Leaf extract administration for 60 days returned all the abnormal parameters to normal levels 359).

Furthermore, extract of Moringa oleifera leaf inhibited the formation of advanced glycation end products by reducing monosaccharide-induced protein glycation 360). Glucomoringin, phenols, flavonoids, quercetin-3-glucoside, fiber, and phenol have been reported to be responsible for antidiabetic activity 361).

Anti-kidney stone activity

Aqueous and alcoholic extracts of Moringa oleifera plant showed anti-urolithiatic activity in a hyperoxaluria-induced rat model 362) and in ethylene glycol–induced urolithiasis model 363).

Diuretic activity

Moringa oleifera leaves, flowers, seeds, roots, and bark extracts increased urine output in rats, extract of leaf showed a dose-dependent diuretic action greater than control but less than hydrochlorothiazide. Campesterol, stigmasterol, β-sitosterol, and avenasterol were responsible for this activity 364).

Anti-allergic activity

Ethanolic extract of Moringa oleifera seeds inhibited passive cutaneous anaphylaxis induced by anti-immunoglobulin G (IgG) antibody and histamine release from mast cells; the mechanism underlying this action could be membrane-stabilizing action 365) and also reduced scratching frequency in an Ovalbumin sensitization model 366).

Anthelmintic activity

Moringa oleifera plant showed potent anthelmintic activity, it took less time to paralyze Indian earthworm Pheretima posthuma 367). In ovicidal assay, ethanolic and aqueous extracts showed 95.89% and 81.72% egg hatch inhibition, respectively, and in larvicidal assay, they showed 56.94% and 92.50% efficacy, respectively 368).

Wound-healing activity

Extracts of Moringa oleifera leaf, dried pulp, and seeds showed a significant increase in hydroxyproline content, wound-closure rate, granuloma-breaking strength, and granuloma dry weight, and a decrease in scar area and skin-breaking strength in incision, excision, and dead space wound models in rats 369).

Studies conducted on the effect of wound healing of Moringa oleifera leaf extract in diabetic animals showed improved tissue regeneration, decreased wound size, downregulated inflammatory mediators, and upregulated vascular endothelial growth factor in wound tissues 370) and remarkable antiproliferative and anti-migratory effects on normal human dermal fibroblasts 371).

Anti-bacterial activity

Ethanolic extract of Moringa oleifera leaf showed antimicrobial activity against all the tested bacteria 372). Chloroform extract reported activity against pathogens such as Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli, and Vibrio cholerae 373).

Ethanolic extracts of Moringa oleifera root and bark possessed antifungal activity against Aspergillus niger, Neurospora crassa, Rhizopus stolonifer, and Microsporum gypseum 374) and also showed inhibitory activity against Leishmania donovani 375). Many studies suggest that extracts of Moringa oleifera seeds could be a potential option to purify water sources as it inhibited bacterial growth in agar and nutrient medium 376).

Methanolic extract of Moringa oleifera leaves inhibited urinary tract pathogens, such as Staphylococcus aureus, Klebsiella pneumoniae, S. saprophyticus, and E. coli 377).

Flavonoids, tannins, steroids, alkaloids, saponins, benzyl isothiocyanate, and benzylglucosinolate were found to be responsible for antimicrobial activity 378), whereas pterygospermin was found to be responsible for antifungal activity 379).

Immunomodulatory activity

Methanolic extract of Moringa oleifera plant stimulated both humoral and cellular immune response 380). In addition, extract showed an increase in optical density and stimulation index, indicating splenocyte proliferation 381).

Antidiarrheal activity

Extract of Moringa oleifera seeds showed significant reduction in gastrointestinal motility and were found to be effective in castor oil induced diarrhoea in male Wister rats 382). Antidiarrheal activity can be attributed to phytochemical ingredients such as tannins, saponins, and flavonoids 383).

Miscellaneous effects

Moringa oleifera leaf extract exhibited a reduction in unwanted sebum secretions from sebaceous gland during winter in humans 384). A systematic review and meta-analysis have clearly accounted Moringa oleifera plant as a galactagogue (help a breastfeeding mother to increase her breast milk supply) 385). Methanolic extract of Moringa oleifera root showed local anesthetic action in frog and guinea pig models 386). Significant CYP3A4 inhibitory effects was exhibited by Moringa oleifera leaf extract 387). Thus, Moringa oleifera has a great potential for herb–drug interactions.

Moringa oleifera side effects

Moringa oleifera is not entirely safe, as many studies have found various compounds that have been associated with major liver, kidney, hematological and other diseases 388). Roasted Moringa oleifera seeds contain potential mutagens such as 4-(α-lramnopyranosyloxy)-benzylglucosinolate, which increase the proportion of micronucleated polychromatophilic erythroblasts, indicative of some degree of genotoxicity 389). The leaf has a high concentration of saponins, which can be potentially harmful for vegetarians, as their consumption reduces the bioavailability of divalent and trivalent metals such as zinc and magnesium 390). Moringin alkaloids, spirochin and the phytochemical benzothiocyanate have been found in the root and bark, toxic substances that predominate in the root and bark; the leaf was therefore identified as the safest edible part 391).

It is also perceived that Moringa oleifera could adversely slow down the breaking down of substances in the liver 392). In that regard, Moringa oleifera could reduce the process of breaking down some medication in the liver. This could progress to cirrhosis and liver failure resulting in malnutrition and weight loss, as well as decreased cognitive function 393). In addition, Moringa oleifera has been noted to be a good regulator of insulin 394). Therefore, patients suffering from lack of insulin are bound to have adverse reductions in their sugar levels when using Moringa oleifera for medicinal purposes 395). It is hypothesised that it could decrease the blood sugar to even lower levels when used in combination with other modern medications 396).

A study by Barichella et al. 397) assessed the use, acceptability and safety of Moringa oleifera on children in Zambia. With regards to safety concerns, supplementation of 14 g per day of Moringa oleifera powder was deemed safe for children and adolescents both in the short and long term. Barichella et al. 398) also noted that mild nausea was reported in 20% of the children at various age groups when meals were supplemented with 20 g of Moringa oleifera daily. These side effects were deemed acceptable by the Ethics Committee 399). Overall, the findings of this study underscore the fact that despite the lack of safety information on the utility of Moringa oleifera, there are no scientifically proven side effects of Moringa oleifera to this date 400).

Moringa oleifera contraindications

Moringa oleifera contains harmful chemicals such as alkaloids and other phytotoxins, which when consumed in high doses have potentially nerve-paralysing properties and other adverse effects 401). Some of these phytochemicals include moringine, moringinine, estrogene, pectinesterase and phenols including tannin 402). There are also unconfirmed reports that Moringa oleifera stems and roots potentially contain harmful phytochemical constituents, especially to pregnant women. Specifically, it is suspected that these elements of Moringa oleifera contain phytochemicals which have a potential of facilitating uterus contraction, leading to miscarriages in pregnant women. It is also suspected that it has the ability to prevent implantation in women, hence it has to be avoided by those attempting to conceive 403). Some scientists suspect that the Moringa oleifera extracts from the roots have a potential of even causing paralysis and death. However, it is important to note that there are no major harmful effects of Moringa oleifera on humans that have been put forth by the scientific community to this date 404). Based on the studies, and ongoing research, that has been conducted to date on both humans and animals, no adverse effects have been noted from Moringa oleifera products 405). Although research is still ongoing, currently there are no scientifically confirmed toxic and harmful effects of Moringa oleifera extracts and products on both humans and animals.

Moringa oleifera summary

Moringa oleifera is one of the most studied and used plants. Its uses stretch from food and medicinal uses to water purification, biopesticide and production of biodiesel. Moringa oleifera leaves, the most used part of the plant, are rich in vitamins, carotenoids, polyphenol, phenolic acids, flavonoids, alkaloids, glucosinolates, isothiocyanates, tannins and saponins. In addition, even if leaves present high variation in the amounts of bioactive compounds as a result of the genetic characteristics of the plant, the environmental conditions to which the plant is subjected and the post-harvest treatments as well, they present greater amounts of these compounds than fruits, vegetables and other plants generally used in human nutrition 406). On the other hand, the high leaves content of oxalates and phytates could limit the intestinal adsorption of minerals. Therefore, this aspect should be taken in to account for future nutritional researches focused on using Moringa oleifera as minerals supplementation.

The high contribution in bioactive compounds may explain the pharmacological properties ascribed to Moringa oleifera leaves. Many test tube and animals studies have widely confirmed numerous pharmacological properties. However, few evidences on human beings are available. Therefore, it is too early to recommend Moringa oleifera leaves as medication in the prevention or treatment of diabetes, cardiovascular disease, dyslipidemia, cancer and infective diseases. Moreover, Moringa oleifera is not entirely safe, as many studies have found various compounds that have been associated with major liver, kidney, hematological and other diseases 407). Roasted Moringa oleifera seeds contain potential mutagens such as 4-(α-lramnopyranosyloxy)-benzylglucosinolate, which increase the proportion of micronucleated polychromatophilic erythroblasts, indicative of some degree of genotoxicity 408). The leaf has a high concentration of saponins, which can be potentially harmful for vegetarians, as their consumption reduces the bioavailability of divalent and trivalent metals such as zinc and magnesium 409). Moringin alkaloids, spirochin and the phytochemical benzothiocyanate have been found in the root and bark, toxic substances that predominate in the root and bark; the leaf was therefore identified as the safest edible part 410). Although research is still ongoing, currently there are no scientifically confirmed toxic and harmful effects of Moringa oleifera extracts and products on both humans and animals 411).

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